Variable-speed transmission



Apk-1E 5, 3949. D. w. KELBEL VARIABLE SPEED TRANSMISSION Filed May 18, 1944 Patented Apr. 5, 1949 VARIABLE-SPEED TRANSMISSION Donald W. Kelbel, Muncie, Ind., asslgnor to Borg- Warner Corporation, Chicago, Ill., a corporation of Illinois Application May 18, 1944, Serial No. 536,106

This invention relates to power transmitting devices adapted to produce a variable speed and torque ratio drive between the driving and driven structures thereof. For purposes of illustration it will be described with reference to an innitely variable hydro-dynamic Itorque convertor comblned with gearing, although it is to be understood that the invention is not to be limited to any particular type of innitely variable torque multiplying device.

The principal object of this invention is to provide an innitely variable torque multiplying like wherein an infinitely variable torque multiplying device is combined with differential gearing in a manner to provide a two-path power flow arrangement for certain speeds of the vehicle. and above the predetermined speed to provide a purely mechanical overdrive ratio.

A more specific object of this invention is to provide a transmission for an automotive vehicle in which a vaned type hydro-dynamic torque convertor is combined with planetary gearing in such a manner that up to a certain vehicle speed the torque is transmitted through the gearing in such a manner that part of the torque is trans-fA mitted directly to the load and the remainder is transmitted through the torque convertor, with means for rendering the convertor ineffective and at the same time changing the drive to a purely mechanical drive through the gearing to produ-ce an overdrive ratio. Y

These and other objects and features of the invention will become apparent from the following detaileddescription when taken together with the accompanying drawing in which:

Fig. 1 is a schematic diagram of the principal torque transmitting elements of the transmission; and

Fig. 2 is a partial section through the principal torque transmitting elements shown in their preferred arrangement and proportion.

Referring now to Fig. 1 for a general description of the invention, the driving structure is shown at Ill and may comprise a drive shaft II which is connected to a suitable prime mover (not shown) such as an internal combustion engine and is adapted to drive an automatic friction clutch I2 which, in turn, drives a differential gear sct I3 in such a manner that part of the torque is transmitted directly to a driven struciure AI4 and part is transmitted to an infinitely variable torque multiplying device I5 which is likewise connected through the gearing to the driven structure I4.

4transmission for an automotive vehicle or the Gearing I3 is comprised of an internal or ring gear I6 which meshes with planet gears I1 of the one` or more pairs of intermeshed planet gears I'l and I8, and a sun gear I9 which meshes with the planet gears I8 of said pairs of intermeshed gears. A carrier 20 supports the, pairs of planet gears I1 and I8 and forms part of the driven `structure I4. A brake 2l is adapted to hold sun gear I9 against rotation to provide an overdrive ratio through the planetary gearing I3 when the ring'gear 'I 6 is the driver.

The innltely variable torque multiplying device I5 is comprised of an input element 22, an output element 23 and a reaction element 24, output element 23 being directly connected to carrier 20 and thus to driven structure I4.

When brake 2l is released the drive will be from drive shaft II through clutch I2 to gearing I3 wherein it is split into two paths, part of it being transmitted to output structure I4 and the remainder being transmitted to torque convertor I5 where it is multiplied before being impressed upon output structure I4. The speed and torque ratio between drive shaft I I and output structure I4 will vary depending upon the load, the ratio being highest and producing the greatest torque multiplication when the load is greatest and diminishing in infinite steps until it approaches a one-to-one ratio. It is contemplated that a further torque multiplication will be provided between the driven structure and the load and that this further torque multiplication will be in the neighborhood of 4.25 to 1. When used in an automotive vehicle this additional torque multiplication will be effected by means of the rear axle differential gearing. With such additional torque multiplication it is desirable to use an overdrive ratio between drive shaft I I and driven structure I4 so as to take full advantage of the torque available in the prime mover.

When brake 2| is engaged to hold sun gear I9 against rotation while ring gear I6 is being driven, the dual planet construction will cause carrier 20 to be driven at an overdrive with respect to drive shaft II and this overdrive will be transmitted directly to driven structure I4.

Referring now to Fig. 2 for a detailed description of a preferred embodiment of the invention, the drive shaft I I is shown provided with a flange 25 to which'is bolted a ily wheel 28 having a starting gear 21 secured to the periphery thereon. Said flywheel 26 has axially extending lugs 28 to which is bolted a clutch cover 29. A reaction plate 30 is supported from and driven by fly wheel 26 by suitable means (not shown) and is connected to cover 28 through a'Bellville type spring- 3I. Reaction plate l0 supports a plurality of centrifugal weights 32 which pivot at 3l on reaction plate 38 and transmit centrifugal force through struts 34 to a pressure plate 3l. A clutch plate 88 is mounted between pressure plate 35 and fly wheel 2l and is adapted to transmit torque from the ily wheel through a hub member 3'! to a flanged forging 38 to which it is splined. Said flanged forging 28 supports and drives ring gear I8 which, as previously described with reference to Fig. 1, meshes with a' planet pinion Il mounted on carrier 28. Pinion I8 meshes with pinion I1 and also with sun gear I8 which may be formed at one end of a hollow shaft 38. Carrier 28 is in turn splined to a shaft 40 which is part of the driven structure i4 shown in Fig. 1. Said shaft 48 passes through hollow shaft 39 and terminates in a gear 4I and a positive clutch element 42. The functions of gear 4I and clutch 42 will be described hereinafter.

Torque convertor I is comprised of a vaned impeller 22 which may be formed as a casting having a flange 4I by which it is rotatably .mounted on hollow shaft 39. Torque convertor I5 is also provided with a vaned turbine member 23 which forms a portion of the housing for the convertor and is bolted to another portion 44 of the housing, the latter being directly connected to carrier 28 and hence directly associated with the output structure I4. Also bolted to turbine memiber 23 is a forging 45 which is connected to the drive pinion 48 of a pump 4l mounted in a re duced portion 48 of transmission housing 48. Torque convertor I5 also includes a vaned stator element 24 which is likewise in the form of a casting having a flange 50 by which it is rotatably mounted upon a fixed sleeve 5I surrounding hollow shaft 39 and extending into portion 48 of housing 48 to which lt is non-rotatably anchored. A roller-and-cam type coupling52 automatically prevents relative rotation between stator 24 and sleeve 5I when stator 24 tends to rotate in a reverse direction relative to drive shaft Il but permits such relative rotation when the rotational tendency is in a forward direction. All of the vanes of the convertor are preferably immersed in a fluid under pressure supplied by pump 41 or some other suitable source of iiuid under pressure.

Brake 2| is comprised of one or more friction discs 53, which are splined at 54 to hollow shaft 35, and non-rotatable plates 55 between which friction discs 53 are adapted to be compressed. Reduced portion 48 of housing 48 is closed at its rig-ht hand end (Fig. 2) by a casting 58 which together with reduced portion 48 forms an annular cylinder 5l in which is retained a piston 58. Said piston 58 when moved to the left (Fig. 2) under the influence of fluid under pressure, will compress friction discs 53 between plates 55 and hold hollow shaft 39 and its associated sun gear I9 against rotation. Because of the dual planet arrangement, shaft 40 will be driven at an over speed with respect to driving shaft il when ring gear I8 is the driver and sun gear i9 is the reaction element.

It will be observed that since turbine element 23 is directly connected to carrier 20, said turbine member 23 will be compelled to rotatewith the carrier Whenever the sun gear I9 is stationary as in overdrive. If impeller member 22 were rigidly attached to sleeve 39 under such conditions a tremendous power loss would result in the convertor. To eliminate this power loss the connection between sun gear I8 and its associated sleeve 28 and impeller 22 is made automatically releasable so thatgpump impeller 22 may rotate ahead of'sleeve 3l if conditions should warrant such-movement but will be driven by hollow shaft 38 if said shaft tends to rotate ahead of impeller 22. The releasable connection for accomplishing this result is shown at 58 and comprises a rollerand-cam type overrunning clutch of any well known design having a plurality of rollers 88 controlled by a roller cage 8| in such a manner with respect to cams 82 formed on sleeve 38 that sleeve 38 will drive pump element 22 when the latter tends to lag behind the sleeve and will be free of impeller 22 when the latter tends to rotate ahead of the sleeve.

Under certain conditions it is desirable to drive shaft Il from driven structure I4, as for example when it is desired to start the engine of a vehicle by towing or pushing the vehicle'. Since clutch l2 is energized only from the driving shaft it is necessary to provide a substitute connection between the driving and driven structures. To that end a plate 83 is bolted to drive shaft Ii and is provided with axially extending teeth 84. A corresponding set of teeth 851s formed in the end of flanged forging 33 to which hub 31 of friction plate 38 is splined. Said flanged forging 38 is adapted to slide axially on carrier 20 so as to engage teeth 55'with teeth 84. It is contemplated that the teeth of differential gearing I3 will be helical and out in such a direction that when drive shaft Il is driving and clutch I2 is operative to drive ring gear I8, the latter will be urged by relative torque reaction in an axial direction to the right as shown in Fig. 2 until flange 38 abuts carrier 28 and that when carrier Y 28 is the driver and ring gear I6 is the driven member, the torque reaction will be such as to move ring gear I6 and its associated forging 38 to the left as shown in Fig. 2 to engage teeth 65 with teeth 64.

Thus in order to startthe prime mover associated with shaft II by towing or pushing the vehicle, shaft 40 is rotated, thereby rotating carrier 20 and turbine element 23 and also tending to rotate sun gear i8. The torque reaction between planet pinions Il and ring gear I6 will be such as to cause engagement between teeth 65 and 64 thereby making ring gear I6 the load member for the drive. Sun'gear I8, however, will tend to rotate freely but at an overspeed with respect to carrier 2li and therefore impeller 22 will be effective to energize the fluid within torque converter I5 and thus tend to lock carrier 20 to sun gear i8. This locking tendency will result in a driving eort which will be impressed upon ring gear I8 and transmitted through teeth 65 and 84 directly to drive shaft il. Just-as soon as the prime mover takes over the drive, the torque reaction on ring gear I6 will be in the opposite sense and the ring gear and its associated forging 38 will be moved to the right as shown in Fig. 2 to disengage teeth 65 from teeth 84.

Since pump 41 is driven only when turbine element 23 of torque converter I5 is rotating and .since turbine element 23 rotates only when the driven structure -I4 and shaft 40 are rotating it will be apparent that whenever the vehicle is at rest and the engine is idling, as for example when the vehicle is at the curb preparatory to starting or is at a stop light, there will be no pressure available to supply uid to converter l5 and if at that time the converter should be substantially. empty through normal drainage, there may be a time lag between the speed up of the engine preparatory to getting away and the building up oi' sulcient torque within the-converter to start the vehicle. For this reason a second pump 66 ls provided, the second pump being driven directly by hollow shaft 39 and sun gear I9. Thus when shaft 40 is stationary under the conditionsjust described and pump 41 is not being driven. sun gear I9 will be rotated at an'overdrive with respect to shaft II so that even though drive shaft II is idling, sun gear I9 and its associated sleeve 39 will be rotating at a suillciently high speed to energize pump 66 and maintain converter I5 full of fluid under pressure. Thus converter I will be immediately eiective to multiply torque and accelerate the vehicle when drive shaft II is speeded up. It is understood that suitable conduits (not shown) will be provided between pumps 41 and 66 and converter I6.

Inasmuch as the combined torque converter and planetary gearing above described does not provide a reverse drive, an auxiliary mechanism is supplied for this purpose. This auxiliary mechanism is shown generally at 61 and-includes `in addition to gear 4I and clutch teeth 42 the cluster gear 68 rotatably mounted upon a coun tershaft 69 and comprising a gear 10 meshing with gear 4I and a gear 1I which meshes with ldifferential gearing connecting said structures and comprising a ring gear driven by the input structure, a planet carrier connected to drive the output structure, a pair of intermeshed planet gears carried by the planet carrier, and a sun gear,` one of saidv planet gears meshing with the ring gear and the other with the sun gear; an ininitely variable torque multiplying device having driving, driven and reaction elements; oneway drive means connecting the sun gear to the driving element in a manner to release drive therebetween when the driving element tends to rotate ahead of the sun gear, means connecting the driven element to the carrier, and releasable means for arresting rotation of the sun gear to provide a fixed overdrive ratio between the input and output structures, said one-way drive means allowing the driving element to rotate free of said sun gear when said overdrive ratio is` operative.

3. A variable ratio torque transmitting mecha- `nism comprising input and output structures.

an idler gear 12, the latter meshing with a gear 13 mounted for rotation on a propeller or load shaft 14. Gear 13 is provided with clutch teeth 15 and load shaft 14 has splined thereon a hub 16 on which is slidably splineda shift collar 11. Said shift collar 11 may assume either a neutral position as shown in Fig. 2 wherein neither clutch teeth'42 nor clutch teeth 15 is engaged thereby,

' or it may be slid in either direction to engage one or the other of said clutch teeth. When engaged with clutch teeth 42 a direct drive is established between shafts 40 and 14. When it is engaged with teeth 15 a reverse drive is established between shaft 40 and 14 through gearings It is understood that suitable bearings. fasteners and connecting elements will be used throughout the preferred embodiment, such bearings, fasteners and connectors being readily vdesigned byone skilled in the art and hence not described in detail herein. It is further understood that the foregoing description is merely illustrative of a preferred embodiment of the invention and that the scope of the invention therefore should not be limited thereto but should be determinedby the appended claims.

I claim:

1. A variable ratio torque transmitting mechanism comprising input and output structures, differential gearing connecting said structures and comprising a ring gear driven by the input structure, a planet carrier connected to drive the output structure, a pair of intermeshed planet gears carried by the planet carrier, anda sun gear, one of said planet gears meshing withthe yring gear and the other with the sun gear; an infinitely variable torque multiplying device hav'- ing driving, driven and reaction elements; re-

leasable drive means connecting the sun gear to the driving element, means connecting the driven element to the carrier, andv releasable means for arresting rotation of the sun gear to provide a xed overdrive ratio between the infput and output structures, said releasable drive means allowing the driving element to rotate free of said sun gear when said overdrive ratio is operative.

2. A variable ratio torque transmitting mechanism comprising input and output structures,

differential gearing conecting said structures and comprising a ring gear driven by the input structure, a planet carrier connected to drive the output structure, a'pair of intermeshed planet gears carried by the planet carrier, and a sun gear, one of said planet gears meshing with the ring gear "and the other with the sun gear; a hydraulic torque convertor having pump, turbine and stator elements, one-way drive means connecting the sun gear to the pump element in a manner to permit the pump element to overrun the sun gear, means connecting the turbine element to the carrier, and releasable means for arresting rotation of the sun `gear to provide a fixed overdrive ratio between the input and output structures, Asaid one-way drive means allowing the pumpelement to rotate free of said sun gear When said overdrive ratio is operative.

4. A variable ratio torque transmitting mechanism comprising an input structure, an output shaft, differential gearing connecting the input structure to the output shaft'and comprising a ring gear driven by the input structure, a planet carrier connected to drive the output shaft, a pair of intermeshed planet gears carried by the planet carrier, and a sun gear, one of said planet gears meshing with the ring gear and the other with the sun gear; said output shaft passing through the differential gearing and having one end in proximity to the input structure; an innitely variable torque multiplying device having driving, driven and reaction elements, a hollow shaft surrounding the output shaft and passing through the infinitely variable torque multiplying device, said shaft being directly driven by the sungear at one end, releasable drive means connecting the hollow shaft to the driving element, means connecting the driven element to the carrier, and releasable brake .means connected' to the other end of the hollow shaft for arresting the sun gear to provide a Ifixed overdrive ratio between the inlput structure and the output shaft.

5. A variable ratio torque transmitting mechanism as described in claim 4, and a pump connected to the driven element for supplying fluid to the infinitelyvariable torque multiplying device.

6. A variable ratio torque transmitting mechanism as described in claim 4, anda pump driven bythe hollow shaft f or supplying fluid under pressure to the infinitely variable torque multil maar 7 piying device when the driven element is stationary.

7. A variable ratio torque transmitting mechanism as described in claim 4, a xed cylindrical member surrounding the hollow shaft and a releasable connection between the fixed cylindrical member and the reaction element.

8. A variable ratio torque transmitting mechanism comprising an input structure. a driven shaft, a diierential gearing connecting the input structure with the driven shaft and comprising a ring gear adapted to be driven by the input structure, a planet carrier connected to drive the driven shaft, a pair of intermeshed planet gears carried by the planet carrier, and a sun gear, one of said planet gears meshing with the ring gear and the other with the sun gear; a hydraulic torque convertor having pump, turbine and stator elements; one-way clutch means for connecting the sun gear to the pump element and constructed to permit the pump element to overrun the sun gear, a housing for the convertor rotatable with the turbine element and connected to the planet carrier, a hollow shaft extending through the torque convertorV and adapted at one end to be driven by the sun gear, a brake adapted to cooperate with the other end of the hollow shaft to hold the shaft and sun gear against rotation to provide a fixed overdrive ratio between the input structure and driven shaft, a xed cylindrical element surrounding the hollow shaft, one-way connecting means between the stator element and the fixed hollow cylindrical member, a pump for supplying the convertor with fluid under pressure and adapted to be driven by the hollow shaft, and a second pump adapted to be driven by the housing.

9. A torque transmitting mechanism comprising input and output structures, an automatic clutch energized by rotation of the input structure and connected to receive drive therefrom, means for transmitting the drive from the clutch to the output structure, said means including an axially reciprocable element which is responsive to torque, and a clutch for by-passing the automatic clutch and connecting the output structure to the input structure, said clutch being energized by the torque responsive element.

10. A torque transmitting mechanism as described in clam 9, said means for transmitting the drive from the automatic clutch to the output structure comprising gearing having helical teeth such that axial thrusts are developed, and said axially reciprocable element being directly connected to the gearing.

11. A torque transmitting mechanism as described in claim 9, said means for transmitting the drive from the automatic clutch to the output structure comprising planetary gearing having helical teeth such that axial thrusts are developed and including a ring gear driven directly by the automatic clutch, and said axially reciprocable element being directly connected to the ring gear.

12. A variable ratio torque transmitting meehanism comprising input and output structures, differential planetary gearing connecting said structures and comprising a ring gear element, a planetary carrier element, a pair of intermeshed planet gears carried by said last mentioned element, a sun gear element one of said planet gears meshing with said sun gear element and the other with said ring gear element, one of said elements being driven by said input structure, another of said elements being connected to said output structure, a torque multiplying de. vice having driving and driven members. automatically releasable drive means connecting one of said elements to said driving member, means connecting another of said elements to said driven member, and releasable means for arresting the element connected to said driving member to provide a fixed overdrive ratio between the input and output structures, said releasable y) first-mentioned clutch and connecting the input and output shafts and energized by the torque responsive element whereby the second-named clutch is engaged when the output shaft is driven while the input shaft is stationary.

14. A 'torque transmitting mechanism comprising input and output shafts, a centrifugal clutch energized by rotation of the input shaft and connected to receive drive therefrom, means connecting said clutch and said output shaft for 30 transmitting the drive from the clutch to the output shaft, said means including a torque responsive element, and a clutch for bypassing the first-mentioned clutch and connecting the input and output shafts and energized by the torque 35 responsive element whereby the second-named clutch is engaged when the output shaft is driven while the input shaft is stationary.

15. A variable ratio torque transmitting mechanism comprising input and output structures,

wdierential planetary gearing connecting said structures and comprising a ring gear element, a. sun gear element, a planetary carrier element, planetary gears carried by said last-mentioned element. and meshing with said sun gear and ring gear elements, one of said elements being driven by said input structure, another of said elements being connected to said output structure, a hydrodynamic coupling device having driving and driven members, releasable drive means connecting one of said elements to said driving member, means connecting another of said elements to said driven member, and releasable means for arresting the element connected to said driving member to provide an overdrive speed ratio between the input and ourtput structures. said releasable drive means being released to allow rotation of said driving member free from its associated element when the overdrive speed ratio is operative.

16. AA variable ratio torque transmitting mechanism comprising input and output structures, planetary gearing connecting said structures and comprising three elements adapted to receive and deliver power to and from the gearing, -one of said elements being driven by said input structure and another of said elements being connected 'to said output structure, a hydrodynamic coupling device having driving and driven members, releasable drive means connecting one of said elements to said driving member, means connecting another of said elements to said driven member, and releasable means for arresting the element connected to said driving member to provide an overdrive speed ratio between the input u and output structures, said -releasable drive means being released to allow rotation of said driving member free from its associated element when the overdrive speed ratio is operative.

17.` A variable ratio torque transmitting mechanism comprising input and output structures, planetary gearing connecting said structures and comprising three elements adapted to receive and deliver power to and from the gearing, one of said elements being driven by said input structure and another of said elements being connected to said output structure, a torque multiplying device having driving and driven members, automatically releasable drive means connecting one of said elements to said driving member, means connecting another of said elements to said driven member, and releasable means for arresting the element connected to said driving' member to provide an overdrive speed ratio between the input and output structures, said releasable drive means being released rto allow rotation of said driving member 'free from its associated element when the overdrive speed ratio is operative.

DONALD W; KELBEL.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Burtnett Feb. 15, 1944 

